Inclusion Body Myositis (IBM).

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Introduction:

This web page presents information on inclusion body myositis. There are two main types; a spontaneous type that just strikes "out of the blue." It is the common type, known as spontaneous inclusion body myositis, and is usually abbreviated as sIBM. The second type, Hereditary inclusion body myopathy (HIBM) is a very rare group of inherited disorders; passed on from parents to children. How the two types may be related is unknown.

This page is a good starting point for a person interested in sIBM and contains information suitable to take to a family physician. The site provides two levels of information, basic introductions and critical overview articles and also a more complex body of research / medical information, including summaries / reviews of some of the major scientific literature on sIBM.

Key points:

As more and more cells are involved, the muscle becomes weaker and weaker.

Not all muscles are impacted, for example, the heart is not affected.

Muscles are not all equally affected at the same time.

Different muscles groups are affected at different rates: the lower leg muscles show the greatest decline, followed by forearm and upper leg muscles.

After symptoms of sIBM first become noticable, exactly how it will affect you, and how fast it will progress are difficult to predict. sIBM is quite variable between different people.

The illness is chronic: once you get it you have it all your life.

The illness is progressive: the disabilities keep accumulating and you get worse and worse as time goes on.

In most cases, the muscles of the arms and legs are affected first and weakness in the hands and tripping are common first symptoms.

The common early presentation of weakness is shown in red (above).

Muscle weakness may occur in the diaphragm and the esophagus (illustrated in orange, above).

The illness can cause severe disability and often necessitates use of a wheelchair.

The illness is age related; it usually occurs after age 40 and becomes more common in the population as people age.

Researchers do not understand what causes sIBM.

The illness can be difficult to diagnose (can take up to 5 years) and is often first mistaken as polymyositis.

No effective treatment has been developed yet.

The most effective coping strategy is watching for, and managing, complications and the prevention of injuries due to falls.

A common serious complication is weakness in swallowing (dysphagia) that can cause choking or aspiration (taking food into the lungs) causing pneumonia (sometimes a cause of death). Swallowing involvement is a critical factor that should be investigated as soon as an IBM diagnosis is made.

Another serious complication is respiratory impairment caused by weakness of the diaphragm. Respiratory involvement is a critical factor that should be investigated as soon as an IBM diagnosis is made. Respiratory dysfunction can be identified, treated and monitored. The most common causes of death in IBM patients are complications due to respiratory failure and aspiration pneumonia (associated with both weak respiration and dysphagia - weakness in swallowing). Therefore, ongoing monitoring and awareness of these issues is highly recommended to both the patient and his or her physicians.

sIBM does not appear to be directly genetic (it is not passed on to children) however, a complex pattern of genetics may be involved in creating a predisposition to getting it.

The illness is considered a type of muscle disease, usually listed under the umbrella of muscular dystrophy diseases.

Traditionally, corticosteroids were used in an attempt to treat sIBM. However, research shows that chronic use of these medications is ineffective and may even worsen the long-term course of the illness.

A second type of IBM, Hereditary inclusion body myopathy (HIBM) is a very rare group of disorders, strikes very early (18-22) and is inherited; passed on from parents to children. HIBM is most common in the Iranian Jewish (where 1 in 15 are carriers of HIBM and 1 in 1000 Iranian Jews have the disease: very high numbers) and some Japanese communities.

Theories of sIBM

After nearly 30 years of research, the basic causes of IBM remain unknown.

Three basic theories have been proposed over the years. (presented in the order of likelihood based on contemporary research)

1). The immune system is somehow involved in damaging the muscle cells, then causing protein abnormalities.

3). An older theory was that a virus is the cause, however, no virus has ever been identified.

Until the basic causes are discovered, a specific treatment will remain elusive.

Research

There are two main approaches to research; 1) general research into muscles (and muscle diseases) and 2) research specifically focused on IBM.

1) General Research

The causes of many muscle diseases are unknown and in turn, few specific treatments are available. Until more specific treatments are developed, researchers are looking into trying to develop general approaches to enhance muscle function.

If researchers could boost muscle function it might be possible to offset the effects of the different muscle diseases. Even a small increase in function could be very important to the patient having one of these illness.

In normal muscle, there is a mechanism to stop muscle growth. Without this inhibitory system, muscle growth could go unchecked. Researchers are trying to take advantage of this inhibitory system. If this system could be short-circuited then more muscle growth would occur. The basic goal is to have the body produce more muscle than normal. The underlying muscle disease will not be treated but with more muscle being produced the overall impact of the disease may be reduced. As mentioned, even small gains might be very important for the affected patient.

An example of a general approach is a drug called Bimagrumab (BYM338) developed by the Novartis pharmaceutical company in Switzerland. This drug has been used to try to produce more muscle in various conditions. In 2013 this drug was approved for use in clinical trials in sIBM. Unfortunately, in their April 21, 2016 quarterly report, MorphoSys AG and Novartis said Bimagrumab "Did not meet its primary endpoint in patients with sIBM" and that the drug failed the Phase IIb/III study.

2) Research specifically focused on IBM

Research specifically focused on IBM attempts to understand how the disease operates and what causes it. The basic cause of IBM is not currently understood and this is a major focus of IBM research.

Most research on the treatment of IBM has looked at using existing medications and examining their impact on IBM. Generally speaking, no medication has shown significant improvements in IBM patients.

Treatment:

Summary: Based upon research, no treatment is recognized as effective for sIBM (as of 2017). Based upon their experience and opinions, doctors may try medications with IBM patients however, this is a clinical judgment where any possible benefits must be weighed against potential side effects.

"Conventional immunotherapies, albeit effective in other forms of myositis, seem to have only a transient or no beneficial effect on disease progression of IBM. So far, no established evidence-based treatment exists and therapy recommendations are based on expert opinion." From: Update on Treatment of Inclusion Body Myositis

Unfortunately, it would appear that the side effects of all of the current medications far outweigh any benefits seen in sIBM. The best approach is to manage the complications that may arise from the disease. Evaluation of swallowing and respiration are critical, ongoing issues. Prevention of falls is an important consideration.

A cautionary note: there is a strong tendency for both doctors and patients to "want to do something" -- anything -- to try to slow down or reverse the symptoms of a major debilitating and chronic illness like IBM. For patients, it can be very frightening and frustrating to simply "do nothing." Caution must be used when no significant benefits of treatment can be demonstrated and when treatments all have significant potential side effects.

Management:

When faced with a progressive disabling disease that has no effective and reliable treatment options, day to day management becomes critically important to avoid complications. Management involves two critical components; awareness and prevention. We need to be aware of the possible consequences of inclusion body myositis and be able to proactively prevent complications. Simple and consistent practices can prevent many of the complications that can threaten one's life.

Because this illness is dynamic (it keeps changing over time) and progressive, your symptoms will likely change dramatically over time. People are always having to deal with new issues and new weaknesses and it's important to monitor these changes carefully and try to keep adapting as changes keep occurring. In this disease, coping has to be ongoing and keep up with the changes in the symptoms as they are experienced. (See Coping.)

As muscles in the legs are often affected, this creates a major vulnerability to tripping and falling. Prevention of falls is critical.

Individuals with sIBM whose mobility is restricted need to be aware of complications related to this, including the development of edema and the possibility of developing pressure sores from sitting in one place for long periods.

Potential impacts on respiration (diaphragm weakness) are less common but serious. Awareness of respiratory shallowness, especially while sleeping, is important, leading to proper assessment and management. (see Potential Complications: Respiration).

We must prevent iatrogenic complications. This means complications introduced by efforts to treat the illness. In this case, the most common problem is the harm caused by prednisone. This medication is often prescribed although it has not demonstrated any positive effect and many people needlessly suffer its complications.

Research:

Summary: sIBM is a very complex and challenging disease to research. In approximately the last 40 years of research, much has been learned about the disease, but frustratingly, more remains unknown. The understanding of sIBM and its causes is a very slowly evolving phenomenon.

"For the past two decades, the field of sIBM research has been split with some researchers suggesting that sIBM pathogenesis begins with inflammation leading to myodegeneration and others favouring a primary degenerative myopathy stimulating autoimmunity. Now with emerging therapies aimed at targeting muscle degeneration and other therapies focused on immune modulation, it is essential to understand the connection between these two pathologies. A siloed approach that ignores one or the other will not advance future therapeutics. Instead, additive therapies or dual acting therapies that focus on both aspects of disease pathogenesis will likely need to be employed." From:
http://doi.org/10.1111/nan.12384

Yale IBM Registry.

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Mission Statement:

There are many excellent web sites that present information on various neuromuscular disorders. When I looked at the web, I was struck by how scattered the information was, and the fact that much of the information is very technical. Therefore, the primary intention of this site is to help integrate different sources and to provide background to help the reader cope with complex medical jargon and methods. I am not trying to be comprehensive and I do not want to be redundant and present information that is already covered elsewhere.

Disclaimer:

I am not a medical Doctor and this information is not intended to be read as medical advice nor is it a substitute for medical advice. Please consult your Physician if you have medical concerns. I have done my best to offer a layman's interpretation of this material. Any opinions offered are personal and do not reflect those of my employer. Thanks.